Wahab, the GD used McIntosh 3500 TUBE amps for the tweeter arrays. EVEN the roadies could tell the difference. Wishful thinking? I don't think so. We would have used many more 3500's, but Mac stopped building them by the time we started with the Wall of Sound. The 2300 was a default amp. Powerful, but not as good as the tubes. I made some amps at that time, but I could not get much beyond 25W at that time, at very high quality, without reliability problems.
When it comes to amp sound, I have found if bi or tri amping, the most critical, by far, is the tweeter amp, or let's say above 4KHz. I suspect this is because it is so much easier to handle a signal that is frequency limited, essentially to 5KHz or so. Gives the feedback a chance do to its 'thing' a bit more accurately, and slew rate is not important.
John Meyer and I found this to be so back in 1974, when we made a tri amped, all horn loaded studio monitor. I had to make the power amp, that later became the JC-3, mentioned here at times, and we used Marantz amps for 20-400, and 400-4000 Hz respectively. The 'negative' problems of the Marantz amps, easily heard with STAX Electrostatic headphones, fell away to inaudibility, with the limited range use of these amps.
John Meyer and I found this to be so back in 1974, when we made a tri amped, all horn loaded studio monitor. I had to make the power amp, that later became the JC-3, mentioned here at times, and we used Marantz amps for 20-400, and 400-4000 Hz respectively. The 'negative' problems of the Marantz amps, easily heard with STAX Electrostatic headphones, fell away to inaudibility, with the limited range use of these amps.
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At the time , there were no transistors good enough to design economically
such high power amps.
Indeed, the MI3500 had very good perfs for the time and quite out of reach
when using the SS devices produced back then..
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The Wall of Sound 'components' were in place from early 73 until fall 75 IIRC. They provided great sound in a facility like an Outdoor Stadium, but in a 'small' venue like the Winterland Ballroom the sound was just amazing. When I have purchased performances I had attended like the Winterland 73 set, the difference between the mix and what the system sounded like live were shocking. They were very interested in providing a great audio experience to the concert goers.
Well each musician has his own vertical stack of speakers so it was rather like a large line source, yes the piano and drums were reproduced VERY WELL. I say this from first hand experience. They also used a dual vertically offset mics for the vocals not sure who that was done.
BTW the tweeter array is the speaker grouping in the center stage, it was in an arc that covered close to 180 deg. Correct me if I am wrong John.
Yes, but it could not be MORE than 300W in stereo, whereas modern amps often give more power into lower impedance loads. The 2300 will not do that.
For example a single JC-1 will do more than 800W into 4 ohms. The 2300 in mono would give 600W into 4 ohms, or any other impedance. This is because of the use of the autotransformer. The actual drive impedance might have been 2 ohms or less, in actuality. This can be determined by the +/- 40V supplies that the power amp used for the output stage. We did not particularly like the 2300, but they were rugged, dependable, and available.
For example a single JC-1 will do more than 800W into 4 ohms. The 2300 in mono would give 600W into 4 ohms, or any other impedance. This is because of the use of the autotransformer. The actual drive impedance might have been 2 ohms or less, in actuality. This can be determined by the +/- 40V supplies that the power amp used for the output stage. We did not particularly like the 2300, but they were rugged, dependable, and available.
The bottom line about design and engineering in general is specifying what is and isn't important. So what measurements correlate with how the ear/brain system processes the music and of course which don't matter. Engineering is a process of making trade offs since nothing in the real world is perfect. When an engineer creates a specification for a piece of equipment (if the marketing guys let him 
) it is defining and prioritizing what is important and what isn't so important.
Is it the goal to get vanishing low whatever spec, yeah but not if it comes at the expense of another parameter that is more important to the goal of the project. If the goal is to make the best sounding piece of equipment the designer is tasked with determining which specifications take precedence and which are secondary.
Then there is the issue that no two people hear things and prioritize things exactly the same way either aesthetically or musically.
So we make our choices. Components and topography.
To paraphrase CS Lewis if the devil can keep you from asking the right questions he never has to worry about the answers.
) it is defining and prioritizing what is important and what isn't so important. Is it the goal to get vanishing low whatever spec, yeah but not if it comes at the expense of another parameter that is more important to the goal of the project. If the goal is to make the best sounding piece of equipment the designer is tasked with determining which specifications take precedence and which are secondary.
Then there is the issue that no two people hear things and prioritize things exactly the same way either aesthetically or musically.
So we make our choices. Components and topography.
To paraphrase CS Lewis if the devil can keep you from asking the right questions he never has to worry about the answers.
One of the interesting points of the Wall of Sound system was the differential noise cancelling mic arrangement that they used so they could be in front of the speakers and not get feedback. So no, they did not rely on notch equalization.
There were two omni mics close enough together to be sampling the sound field at effectively the same point. They were combined with reverse polarity, so most of the signal cancelled. When the vocalist stepped up to the pair, he sang directly into one, so there was effectively no cancellation. It may seem unlikely, but the system actually worked.
The microphone system was brilliant, but wasn't used for long. It effectively sampled a pressure differential between the diaphragm pair, giving a "phasey"ness.
IIRC the intent, beautifully achieved, was to put performers and listeners into the same sound field. Giants walked the Earth in those days.
IIRC the intent, beautifully achieved, was to put performers and listeners into the same sound field. Giants walked the Earth in those days.
I just want to say that I believe that many people read this thread, just because there is a lot to learn from successful and experienced audio developers like John, Charles and others.
(And I wonder why people who deny that there are audible differences in high end design participate in in a thread called "Blowtorch preamplifier" at all...)
(And I wonder why people who deny that there are audible differences in high end design participate in in a thread called "Blowtorch preamplifier" at all...)
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100% Agree.
The successful (over decades!) in the marketplace of high quality audio claim things, and those which are either not in this market or not successful are denying.
Putting down their succes solely because of good marketing, bribes, exxagerate prices or other similar things is cheap.
Hi,
The charitable interpretation is that they feel the need to protect the poor ignorant souls reading this thread from being taken in by charlatans, snake oil merchants and the like, who try to convince these poor "marks" that actually all gear does not sound the same and try to somehow take these poor ignorant "marks" money. In other words they are debunking fraudulent claims and protect the consumers from evil schemers that try to become millionaires by peddling stuff that does not really work.
Though truth be told, how this scheme of extracting fabulous wealth from Diy'ers is supposed to work is a mystery to me, making money of DIY'ers is hard work...
The less charitable interpretation is that they have somehow conceived that those who do not comply with "all gear sounds the same" philosophy are having some kind of fun trying all this interesting stuff, fun they are constitutionally incapable of having, so they try to spoil that of others, on the principle that "If I'm not enjoying myself I don't see why anyone else should be having any fun!".
I shall leave it to the readers to decide which rings more true.
Ciao T
The charitable interpretation is that they feel the need to protect the poor ignorant souls reading this thread from being taken in by charlatans, snake oil merchants and the like, who try to convince these poor "marks" that actually all gear does not sound the same and try to somehow take these poor ignorant "marks" money. In other words they are debunking fraudulent claims and protect the consumers from evil schemers that try to become millionaires by peddling stuff that does not really work.
Though truth be told, how this scheme of extracting fabulous wealth from Diy'ers is supposed to work is a mystery to me, making money of DIY'ers is hard work...
The less charitable interpretation is that they have somehow conceived that those who do not comply with "all gear sounds the same" philosophy are having some kind of fun trying all this interesting stuff, fun they are constitutionally incapable of having, so they try to spoil that of others, on the principle that "If I'm not enjoying myself I don't see why anyone else should be having any fun!".
I shall leave it to the readers to decide which rings more true.
Ciao T
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